I just noticed this when I saw a strange “Achievement Unlocked” notification pop up on Reddit. What do you think of this? It seems like a retention tactic to me, like what Amino had with its streak leaderboards, and GameFAQs currently has with streak achievements for logging on ten days in a row and also for all days of a month.
Makes it tempting to start logging in again and making daily comments consisting of nothing but random punctuation marks.
If you really need, you could farm like how bot accounts build up karma. Just use a private subreddit so your system gaming is out of the public eye.